The largest asteroid to pass by Earth in recent years, named 2005 YU55, will fly by on Tuesday, offering scientists and amateur astronomers a chance to scrutinize the large rock. As Brian Vastag reported:

The biggest asteroid to cruise by Earth in 35 years will make its closest approach Tuesday at 6:28 p.m.

Scientists say there is no danger. The 1,200-foot-long charcoal-black space rock, called 2005 YU55, will come no closer than 200,000 miles, just inside the orbit of the moon.

It is too faint to see with the naked eye, but backyard astronomers can spy the asteroid with six-inch or larger telescopes as the nearly spherical rock zooms across the constellations Aquila and Pegasus.

Astronomer Robert McMillan of the SpaceWatch project discovered the asteroid six years ago during a routine sky scan. NASA spends about $5 million each year searching for asteroids that could potentially crash into Earth.

Although no threats have been found, McMillan said, “there’s way more work to be done. Near-Earth objects are something the whole world should be concerned about.”

Scientists from NASA and around the world will be attempting to learn as much as they can from 2005 YU55 as it passes Earth, and will look for signs of water on the asteroid. As Brian Vastag explained:

“It will be scanned and probed and scanned some more,” said Marina Brozovic, an asteroid researcher at NASA’s Jet Propulsion Laboratory.

Starting Friday, Brozovic will ping the approaching asteroid with radar from giant dishes at Goldstone, Calif. She wants to map every crater and boulder while refining estimates of the asteroid’s path, which swings inside the orbit of Venus and then out near Mars, crossing Earth’s orbit.

Meanwhile, telescopes in Arizona and Hawaii will analyze light reflected from the asteroid to determine more precisely what it’s made of. Already scientists know it’s darker than charcoal, because it’s a “C-type” asteroid, heavy with carbon and silicate minerals. Astronomers will also look for signs of water.

Similar asteroids that have plunged to Earth — called carbonaceous chondrites — hold within them amino acids and other building blocks of life.

“These are the objects that probably seeded the early Earth with carbon-based materials and water that allowed life to form,” said Don Yeomans, manager of NASA’s Near Earth Object Program, which tracks space objects that veer close to our planet.

Since a humble start at a single telescope in the 1980s, NASA’s $5 million-per-year asteroid-tracking program has matured to the point where the agency said in September that it has detected more than 90 percent of “planet killer” asteroids, those bigger than one kilometer in diameter. None will hit Earth in the foreseeable future, the agency has said.

For those who want to try to catch a glimpse of 2005 YU55 as it passes by, Elizabeth Flock has some tips for spotting the passing asteroid :

Although there’s no danger of the space rock accidentally hitting our planet, it marks the closest flyby of an asteroid this large since 1976, according to NASA.

Asteroid 2005 YU55, as it is called, won’t be visible to the naked eye, and it will be moving fast, but has some tips on how you can make sure not to miss it:

— Get a telescope with at least a six-inch mirror. You can find beginner telescopes here. “It turns out that YU55 is going to be pretty faint when it flies by,” Scott Fisher, program director of the National Science Foundation’s Division of Astronomical Sciences, told “You will need a decent sized telescope to be able to actually see the object.”

— Watch it in the early evening. It is expected to pass closest to Earth, at 201,700 miles, at 6:28 p.m. The best place to view it is the U.S. East Coast.

— Follow the asteroid’s coordinates at the Jet Propulsion Laboratory Solar System Dynamics Web site, which keeps up an Asteroid Watch to detect, track and characterize potentially hazardous asteroids.

— Get answers in a Washington Post chat with an expert on near-Earth asteroids, National Science Foundation astronomer Thomas Statler, at 1:30 p.m. tomorrow.

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